The present invention relates to flow control devices and pertains particularly to an improved pressure compensated emitter. Due to the costs of water in many areas of the country because of not only its scarcity, but the costs of processing and transporting the water, drip irrigation systems have come in widespread use. Drip irrigation systems typically place small quantities of water either by a low volume spray or by a drip process at precise locations on or about a plant to supply the plant with only the needed amount of water.
In my aforementioned prior application, I disclosd devices for supplying a uniform amount of water over a large range of water pressures. Such devices are essential for large systems and also for systems on uneven terrains, such as on hillsides and the like. For example, the water pressure can vary by a significant amount, such as 30 to 40 pounds over the length of a system. It is essential under such circumstances that all emitters in the system be capable of delivering the same amount of water over the pressure differential range in the system.
Many attempts have been made in the past to develop systems for regulating the flow rate with varying pressures. Such prior art systems are typically effective over small ranges of pressure and in some instances are effective only over a certain specific range requiring a certain minimum pressure in order to begin regulation and be effective over a particular pressure range.
It is desirable to have the ability to deliver the water at a controlled rate over a larger range from just above zero and in a selectable form such as a drip or a spray, etc. It is also desirable that either the form of dispensing as well as the flow rate be selectable without expensive manufacturing techniques.